Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Quem é o escritor de Children of Earth do "dia quatro"?
 ###Tabelas: CREATE TABLE singles:_12_3_titles_9_runners-up (singles:_12_3_titles_9_runners-up_id AUTO_INCREMENT PRIMARY KEY, Outcome VARCHAR, Year VARCHAR, Surface VARCHAR, Opponent VARCHAR, Score VARCHAR) CREATE TABLE ro_ro_passenger_ships (ro_ro_passenger_ships_id AUTO_INCREMENT PRIMARY KEY, Ship name VARCHAR, Year INT, Length VARCHAR, Width VARCHAR, Passengers INT, Vessels INT, Speed INT) CREATE TABLE pga_tour_wins_13 (pga_tour_wins_13_id AUTO_INCREMENT PRIMARY KEY, Date VARCHAR, Tournament VARCHAR, Winning score VARCHAR, Margin of victory VARCHAR, Runner(s)-up VARCHAR) CREATE TABLE high_school_players_and_coaches_of_the_year_1989-1997 (high_school_players_and_coaches_of_the_year_1989-1997_id AUTO_INCREMENT PRIMARY KEY, Year INT, Player VARCHAR, Position VARCHAR, High School VARCHAR, Hometown VARCHAR, MLB Draft VARCHAR) CREATE TABLE episodes (episodes_id AUTO_INCREMENT PRIMARY KEY, Children of Earth VARCHAR, Run time VARCHAR, Writer VARCHAR, Director VARCHAR, Original airdate VARCHAR, Viewers (including HD) in millions VARCHAR)  
SELECT Writer FROM episodes WHERE Children of Earth = "day four"